Implement return for generators

For generators ZEND_RETURN directly calls ZEND_VM_RETURN(), thus passing
execution back to the caller (zend_generator_resume).

This commit also adds a check that only return; is used in generators and
not return $value;.

Zend/tests/generators/errors/generator_cannot_return_error.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Generators cannot return values
+--FILE--
+<?php
+
+function *gen() {
+	return $abc;
+}
+
+?>
+--EXPECTF--
+Fatal error: Generators cannot return values using "return" in %s on line %d

Zend/zend_compile.c

@@ -2615,6 +2615,10 @@ void zend_do_return(znode *expr, int do_end_vparse TSRMLS_DC) /* {{{ */
 	zend_op *opline;
 	int start_op_number, end_op_number;
 
+	if ((CG(active_op_array)->fn_flags & ZEND_ACC_GENERATOR) && expr != NULL) {
+		zend_error(E_COMPILE_ERROR, "Generators cannot return values using \"return\"");
+	}
+
 	if (do_end_vparse) {
 		if ((CG(active_op_array)->fn_flags & ZEND_ACC_RETURN_REFERENCE) && !zend_is_function_or_method_call(expr)) {
 			zend_do_end_variable_parse(expr, BP_VAR_W, 0 TSRMLS_CC);

Zend/zend_generators.c

@@ -140,6 +140,9 @@ ZEND_METHOD(Generator, rewind)
 	generator = (zend_generator *) zend_object_store_get_object(object TSRMLS_CC);
 
 	zend_generator_ensure_initialized(object, generator TSRMLS_CC);
+
+	/* Generators aren't rewindable, so rewind() only has to make sure that
+	 * the generator is initialized, nothing more */
 }
 /* }}} */
 
@@ -158,6 +161,8 @@ ZEND_METHOD(Generator, valid)
 	generator = (zend_generator *) zend_object_store_get_object(object TSRMLS_CC);
 
 	zend_generator_ensure_initialized(object, generator TSRMLS_CC);
+
+	RETURN_BOOL(generator->value != NULL);
 }
 /* }}} */
 
@@ -176,6 +181,10 @@ ZEND_METHOD(Generator, current)
 	generator = (zend_generator *) zend_object_store_get_object(object TSRMLS_CC);
 
 	zend_generator_ensure_initialized(object, generator TSRMLS_CC);
+
+	if (generator->value) {
+		RETURN_ZVAL(generator->value, 1, 1);
+	}
 }
 /* }}} */
 
@@ -212,6 +221,8 @@ ZEND_METHOD(Generator, next)
 	generator = (zend_generator *) zend_object_store_get_object(object TSRMLS_CC);
 
 	zend_generator_ensure_initialized(object, generator TSRMLS_CC);
+
+	zend_generator_resume(object, generator TSRMLS_CC);
 }
 /* }}} */
 

Zend/zend_vm_def.h

@@ -2840,6 +2840,11 @@ ZEND_VM_HANDLER(62, ZEND_RETURN, CONST|TMP|VAR|CV, ANY)
 	zval *retval_ptr;
 	zend_free_op free_op1;
 
+	/* For generators return means to simply stop executing */
+	if (EX(op_array)->fn_flags & ZEND_ACC_GENERATOR) {
+		ZEND_VM_RETURN();
+	}
+
 	SAVE_OPLINE();
 	retval_ptr = GET_OP1_ZVAL_PTR(BP_VAR_R);
 

Zend/zend_vm_execute.h

@@ -2321,6 +2321,11 @@ static int ZEND_FASTCALL  ZEND_RETURN_SPEC_CONST_HANDLER(ZEND_OPCODE_HANDLER_ARG
 	zval *retval_ptr;
 
 
+	/* For generators return means to simply stop executing */
+	if (EX(op_array)->fn_flags & ZEND_ACC_GENERATOR) {
+		ZEND_VM_RETURN();
+	}
+
 	SAVE_OPLINE();
 	retval_ptr = opline->op1.zv;
 
@@ -6894,6 +6899,11 @@ static int ZEND_FASTCALL  ZEND_RETURN_SPEC_TMP_HANDLER(ZEND_OPCODE_HANDLER_ARGS)
 	zval *retval_ptr;
 	zend_free_op free_op1;
 
+	/* For generators return means to simply stop executing */
+	if (EX(op_array)->fn_flags & ZEND_ACC_GENERATOR) {
+		ZEND_VM_RETURN();
+	}
+
 	SAVE_OPLINE();
 	retval_ptr = _get_zval_ptr_tmp(opline->op1.var, EX_Ts(), &free_op1 TSRMLS_CC);
 
@@ -11372,6 +11382,11 @@ static int ZEND_FASTCALL  ZEND_RETURN_SPEC_VAR_HANDLER(ZEND_OPCODE_HANDLER_ARGS)
 	zval *retval_ptr;
 	zend_free_op free_op1;
 
+	/* For generators return means to simply stop executing */
+	if (EX(op_array)->fn_flags & ZEND_ACC_GENERATOR) {
+		ZEND_VM_RETURN();
+	}
+
 	SAVE_OPLINE();
 	retval_ptr = _get_zval_ptr_var(opline->op1.var, EX_Ts(), &free_op1 TSRMLS_CC);
 
@@ -27406,6 +27421,11 @@ static int ZEND_FASTCALL  ZEND_RETURN_SPEC_CV_HANDLER(ZEND_OPCODE_HANDLER_ARGS)
 	zval *retval_ptr;
 
 
+	/* For generators return means to simply stop executing */
+	if (EX(op_array)->fn_flags & ZEND_ACC_GENERATOR) {
+		ZEND_VM_RETURN();
+	}
+
 	SAVE_OPLINE();
 	retval_ptr = _get_zval_ptr_cv_BP_VAR_R(EX_CVs(), opline->op1.var TSRMLS_CC);